Background: Diffusion weighted imaging (DWI) provides a measure of the Brownian motion of
water particles, expressed as the apparent diffusion coefficient (ADC). ADC values have been
shown to be higher at term equivalent age in preterm infants with diffuse excessive high signal
intensity (DEHSI) in white matter (WM). In addition, ADC values in DEHSI were not
significantly different from those in the WM of infants with focal WM injury
(1). Elevated ADC values are associated with a decrease in volume of central
grey matter in preterm infants with no signs of acute injury, suggesting a
failure of growth and abnormal connectivity of these structures (1).

Objective: To develop a simple reproducible method for the measurement of ADC values in the
white matter of preterm infants at term equivalent age using DWI, in order to test the hypothesis
that elevated mean ADC values are associated with lower developmental quotient (DQ) scores at
2 years corrected age.

Subjects: Ethical permission was granted by the Hammersmith Hospital Research Ethics
Committee, and written informed parental consent was obtained for each infant. We obtained
DWI at term equivalent age in 38 preterm infants who had no evidence of overt cerebral
pathology on conventional magnetic resonance imaging.

Methods: Mean WM ADC values at the level of the centrum semiovale were determined. At 2
years corrected age a neurological optimality score was determined (3) and the DQ obtained
using the Griffiths Development Scales. The relationship between mean ADC values and DQ
was examined using linear regression analysis. Clinical data relating to post-natal sepsis,
antenatal steroid exposure, supplemental oxygen, gender, patent ductus arteriosus and inotrope
requirement were collected. Unpaired t-tests were used to assess whether the mean ADC values
were significantly different between clinical groups.

Results: The mean (±sd) ADC value in the WM was 1.385 ± 0.07 x 10-3mm2/s and the mean DQ
was 108.9±11.5. No child had evidence of cerebral palsy at 2 years and the median neurological
optimality score was 75 (range 69-78, optimal range 73-78). There was a significant negative
correlation between mean ADC and DQ (p=0.014). ADC values were significantly elevated in
infants with a history of postnatal sepsis (p=0.03).

Conclusion: These findings suggest that higher white matter ADC values at term equivalent age
in preterm infants without overt lesions are associated with poorer developmental performance in
early childhood. Consequently ADC values at term may be of prognostic value for
neurodevelopmental outcome in infants born prematurely and who have no other imaging
indicators of abnormality.